On-grid domestic battery storage

Coastalwatch

Martyn1981 wrote: »

Is that a daily total, or an 'outside of E7' total?

If the EV, and water can be done by E7, and some of the heating too, then the batt 'only' has to meet the daytime leccy consumption, let's say 5 of the 7, and the daytime ASHP. Maybe that helps a bit?

But, with colder weather needing more heating, and reducing the COP too, I think the numbers are still against you for the worst months.

Hmmm! Have to confess to not taking E7 into account and I can see with it quite a reduction in minimum usable battery size would occur. However, with future energy generation changing dramatically in the coming years and production smoothed out through storage, will the benefits of E7 be in a similar proportion. Further, and if I'm interpreting the figures correctly, after Zeup posted returns of various usages from his model they seldom showed a financial benefit for utilising E7. He did state that the return on a large battery was disproportionate compared to one which hits a sweet spot.

I suspect that it only goes to confirm that with so many variables and future unknowns what a difficult decision it may be to make any time soon. I guess it's going to be sometime before battery prices offer a sensible ROI which is rather frustrating, for we're all shovelling excess energy into the grid which could otherwise be stored and used to reduce peak time demand upon it.
As previously suggested elsewhere maybe one answer is to install a minimum size battery at an early stage then, if/when prices come down and the need arises additional capacity could be acquired later.
The plot thickens, unless of course you know differently!

Coastalwatch

pile-o-stone wrote: »

For those with ASHP, perhaps an alternative differential tariff would be better?
Economy 10 has the following off-peak timings (though these can differ slightly depending on your region / supplier):

12.00am - 5.00am
1.00pm - 4.00pm
8.00pm - 10.00pm
https://sse.co.uk/help/electric-heating/economy-10
You could charge your batteries, EV and run the ASHP using grid energy during the above times and also charge up your battery for use outside those times.
The main drawback with differential tariffs like Econ 7/ Econ 10 is the higher cost of peak electricity, where the energy companies claw back the savings you made during the off peak periods. With a correctly sized battery you can reduce the peak energy periods to practically nothing.
Fitting a lot of insulation would obviously help with reducing energy costs. With an insulated and reasonably air tight house, you could probably get away with only running the ASHP during the economy 10 off peak periods.

Hi PS and thanks for the helpful suggestions. For sure charging the EV and heating at off peak would reduce the size of battery required which I'd previously not considered. I followed the link posted to read further on E10 but unfortunately could not find kWh figures to support it's adoption. I did however go on their website to get a quote from them but unfortunately opting for E10 doesn't appear to show unless it falls under having a Smart meter installed, but again there appeared nothing to suggest this to be the case. Unfortunately their monthly quote, even at the cheapest option was about £10/month more than Bulb who I am currently with. If you have figures then I'd be happy to learn of them please.
Having an instant hot water tap(not boiling) already installed, the qooker option appears very expensive in comparison. We've the recommended insulation installed be it in the loft, cavity walls and modern DG windows and doors so little to be gained there I'm afraid.
Thanks again for your interest and do come back with kWh figures for E10 if you have them please. Oh, we are signed up for renewable energy so this would need to apply as well.

silverwhistle

pile-o-stone wrote: »

a boiler tap (like qooker) that keeps a reservoir of hot water in a vacuum flask, where the heat is maintained by much lower wattage than a standard 3kw kettle element.

Aargh, no! Tea needs freshly boiled water. And surely there are few fellow PVers with 3kw kettles? Think mine is 1.7kw.

It's interesting how domestic PV has made us think about our consumption. My base load is now 52w without refrigeration. I'm off skiing at the end of the month for a couple of weeks and it will be interesting to see consumption during that period with only refrigeration and CH pump going, and the latter rarely.

I'm paying an extortionate unit rate as I'm such a low user that it's worth going zero standing charge, and they recently put their prices up by 24.7%! But any change, such as an EV or somebody moving in with me (they always overfill the kettle ) would change that equation.

It's a bit of a dynamic situation for all of us.

orrery

silverwhistle wrote: »

Aargh, no! Tea needs freshly boiled water. And surely there are few fellow PVers with 3kw kettles? Think mine is 1.7kw.

I had a 500/600W kettle, but it didn't last long. My current small kettle is 1kW.


The real benefit is that, with the small kettle I boil less water - with the large kettle I seem to end up boiling about 1 litre too much.

ASavvyBuyer

silverwhistle wrote: »

And surely there are few fellow PVers with 3kw kettles? Think mine is 1.7kw.

Yes, we changed ours for an 800watt kettle, that holds enough for two large mugs of tea/coffee, etc.

It has already lasted over 3 years, so easily paid for itself.

NigeWick

Had an email from Ecotricity yesterday.

Changes to your Eligibility
5.g. We’ve added a requirement for you to notify us If you install an electricity storage system (e.g. battery storage). You must notify us within 10 working days as this may affect your Eligibility.

I had a Tesla Powerwall 2 fitted last April and wonder what's coming next?

ASavvyBuyer

NigeWick wrote: »

Had an email from Ecotricity yesterday.

Changes to your Eligibility
5.g. We’ve added a requirement for you to notify us If you install an electricity storage system (e.g. battery storage). You must notify us within 10 working days as this may affect your Eligibility.

I had a Tesla Powerwall 2 fitted last April and wonder what's coming next?

Eligibility for what?

The electricity tariff you are on with Ecotricity, or the Solar PV FIT payments?

telatech

I’ve received the same email from ecotricity. I’ve requested further info from them to explain how will this affect the FIT eligibility.

I’m also looking to install a 10 Kw battery as soon as ROI is within 6 years.

Any advice on DC vs AC coupling? AC coupling seem to be less efficient due to the double conversion.

zeupater

telatech wrote: »

I’ve received the same email from ecotricity. I’ve requested further info from them to explain how will this affect the FIT eligibility.

I’m also looking to install a 10 Kw battery as soon as ROI is within 6 years.

Any advice on DC vs AC coupling? AC coupling seem to be less efficient due to the double conversion.

Hi

Depends on whether you're looking to use the storage for anything other than the current PV setup in the future (eg off peak storage, wind, additional PV, cogeneration etc) or are content to dedicate the battery investment to sit on the inverter side of the TGM, in which case there are additional considerations if you're looking to install DC circuits for lighting, contingency etc

HTH
Z

telatech

Thanks. I thought that charging from the grid was possible with a DC coupled battery. My PV setup uses a Solaredge Inverter and according to various online documents it is possible to charge the battery using a profile. Only issue is that their interface is limited to the LG battery only. I wish other cheaper batteries were compatible with their charging interface.